In order to optimize germination percentage and seedling establishment, seed disease and lack of nutrients and water should be minimized during the early establishment of a plant. It is possible to control diseases in germinating seeds by coating the seed before planting with, for instance, pesticides. Seed coating is a technique in which several materials such as fertilizers, nutrients, moisture attractive or repulsive agents, plant growth regulators, rhizobium inocolum, and pestcides are combined with a binder and applied to the surface of the seed. Seed coating leads to increase benefits in seed industry.
A number of patents describe processes for the marking and coating of seeds by active ingredients and film forming compositions. U.S. Pat. No. 5,087,475 discloses a process for the film-coating of materials using a water- and gas-permeable, adhesive film-forming substance, which consists of spraying the film-forming substance on seed materials and drying the seed materials. U.S. Pat. No. 5,470,581 discloses a process for providing an aqueous film-coating from a combination of maltodextrin and cellulosic polymers for and agricultural seeds. The aqueous suspension can be applied by spraying. U.S. Pat. No. 5,849,320 discloses a process for coating a seed with an insecticide. U.S. Pat. Nos. 4,853,429 and 4,881,343 describe an aqueous medium containing a dye or pigment and a binder resin composed of the salt of chitosan and an organic acid for seed colouring. U.S. Pat. No. 5,746,022 discloses a seed colour coating composition containing a solvent, a binder, a colourant and other optional additives. U.S. Pat. No. 4,272,417 discloses a liquid seed coating composition containing a binding agent, an active ingredient and a colouring agent in a liquid medium including water and a polyol. U.S. Pat. No. 4,368,591 discloses seeds that are coated with an active ingredient and between 0.035 and 1.8 grams of titanium dioxide per kilogram of seed. WO 99/66784 discloses a process for coating seeds with a thin coating of a pigment that selectively allows light rays having wavelengths of about 570 to 700 nm to pass there through.
It is important that all components are present on the seed in correct amounts, however, once the seed is coated it is difficult to establish if all components are in fact present in the coating. However, none of the above disclosure teaches how the efficiency of the coating process can be evaluated.
There is however a need to check the quality of the final coating, for instance by confirming the presence of any one individual component of multi-component coating composition, and the relative amount of one of more components.
There is also a need to check the quality of the coating process, i.e. to monitor the efficacy and accuracy of the seed treatment process.
In particular there is a need to monitor the amount of treatment substance successfully loaded on an individual seed as a result of a coating process, which amount is referred to as the distribution, or on a set amount (e.g. per kilogram) of seed as a result of a coating process, which amount is referred to as the recovery.
It is an aim of the present invention to provide means and methods for assessing the quality of a seed coat and the quality and performance of a seed coating process. In alternative embodiments, it is an aim of the present invention to provide proof of origin of seeds or preservation of the identity of the seed.